The present invention relates to a method of controlling the operation of an airbag device, a pretensioner, and the like in a passenger car.
As for an airbag device for protecting an occupant in the event of an accident such as a collision, some methods of controlling the deployment of an airbag have been proposed for increasing the safety. According to these methods, it is determined whether the occupant is an adult or a child and the deployment of the airbag is controlled in case that the occupant is a child. Also as for a pretensioner for winding up a seat belt in the event of a collision, methods for controlling the operation of the pretensioner depending on the determination of whether the occupant is an adult or a child have been proposed.
For determining whether the occupant is an adult or a child, seat load cells are disposed beneath a seat squab for measuring the weight of an occupant sitting on the seat. The measured weight is classified as one of two categories (hereinafter, classifying a value as one of two categories will be referred to as xe2x80x9cbinarizingxe2x80x9d) with reference to a certain threshold value to determine whether the occupant is an adult or a child.
However, these conventional methods require careful consideration when setting the threshold value for determining whether the occupant is an adult or a child. When the occupant wears a seat belt, the tension of the seat belt is also applied to the seat load cells so that the weight of the occupant to be measured by the seat load cells should be heavier than the actual weight of the occupant. Therefore, the threshold value when the occupant wears the seat belt should be set greater than the threshold value when the occupant does not wear the seat belt. To cope with such a demand, there is a way that a buckle switch is provided for detecting the latch between a buckle and a tongue of the seat belt and the setting value of the threshold is changed according to ON/OFF of the buckle switch.
Generally, a controller for controlling the deployment of an airbag and/or controlling the operation of a pretensioner is required to respond at high speed. Accordingly, it is required to make its control logic as simple as possible. Under this situation, it is not desired to conduct a complex logic for changing the threshold value for seat load according to ON/OFF of the buckle switch or a signal from other sensors when determines whether an occupant is an adult or a child based on the threshold value.
On the other hand, the determination of whether the occupant is an adult or a child can be made by using a logic of a device for measuring the seat load by changing the threshold value for the seat load. In this case, the output of a buckle switch and/or other sensor can also inputted into the device for measuring the seat load or the output should be transmitted to the device for measuring the seat load from a controller for controlling the deployment of the airbag, thus complicating the wiring and the logic for information interchange.
The present invention is made under the above-mentioned circumstances and one of the objects of the present invention is to provide a method of suitably controlling an airbag or a pretensioner by determining whether an occupant is an adult or a child by using different threshold values corresponding to ON and OFF states of a sensor, without imposing a burden on an airbag deployment control system and without complicating the wiring and the logic for information interchange.
The aforementioned object is achieved by a method for determining the kind of an occupant sitting on a vehicle seat based on the combination of the weight of the occupant and an ON/OFF signal of a sensor. According to the present invention a method of controlling an actuator according to the kind of the occupant determined to be sitting on the seat is provided. In the method, a load discriminator and an actuator controller are separately disposed. The load discriminator determines the kind of the occupant based on respective threshold values corresponding to ON and OFF signals of said sensor to get respective results and outputs the results to the actuator controller. The actuator controller receives an ON/OFF signal from said sensor, judges the actual kind of the occupant by combining the ON/OFF signal of said sensor and the output of the load discriminator, and controls the actuator based on the result of the judgment.
In this method, the load discriminator determines the kind of the occupant based on the respective threshold values corresponding to the combinations of ON/OFF states of sensors (other than weight sensors) such as a buckle switch, to get respective results and outputs the results to the actuator controller. The load discriminator may receive inputs corresponding to the ON/OFF state of a single sensor or a number of sensors. The actuator controller receives the combination of ON/OFF states of the aforementioned sensors, judges the actual kind of the occupant by combining the combination of ON/OFF states and the output of the load discriminator, and controls an airbag device and a pretensioner based on the result of the judgment. Therefore, this method eliminates the complexity of logic (algorithm) of the actuator controller and eliminates the necessity of inputting the outputs of a buckle switch and/or other sensors into a load discriminator.
According to an alternative embodiment of the present invention a method for controlling the actuation of an airbag protecting an occupant of a vehicle seat is provided. The method includes the step of determining in a load discriminator whether the load applied to the vehicle seat corresponds to a child or an adult using a first threshold load value and generating a corresponding first result. The method further includes determining in the load discriminator whether the load applied to the vehicle seat corresponds to a child or an adult using a second threshold load value and generating a corresponding second result. The second threshold value is selected based on the occupant being protected by a buckled seat belt. The first and second results may be provided to an airbag controller. A determination is made whether a seat belt protecting the occupant is buckled and an input is provided to the controller corresponding to the buckled state of the seatbelt. The method includes judging in the controller whether the occupant is a child or an adult, and controlling the airbag based on the type of occupant.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.